Vin startin with a 8 so 78? it shows to be a 77

I picked up a mustang II the vin shows it to be a 78, first digit is a 8, the last owner lost the title so when I went to the DMV they told me it's a 1977, I said no the vin starts with a 8 so it's a 1978 they said no its a 77? the door tag shows built in July 1977 I had a Marti report ran on it, the first part said the car is a 1978 built in 1977 and sold as a 1977 model? im confused.